In a typical wireless network such as long-term evolution (LTE) network, a particular network device may receive transmissions from multiple other network devices. For example, a base station (BS) may receive uplink transmissions from multiple user equipment (UEs). Since each transmission may originate from multiple transmitters, a certain amount of signaling is required to distinguish each transmitter at the receiver. For example, in current cellular networks, the BS instructs each UE when to transmit and which resources to use during transmission, which implicitly identifies the UE during its transmission. As another example, in current 802.11 networks, stations (STA) append their unique medium access control (MAC) address to each transmission in order to identify themselves as the source of the transmission.
Future networks are expected to be a hybrid between current cellular networks and current 802.11 networks, where the signaling is reduced greatly with blind detection of transmissions. For example, instead of a BS directly instructing UE on how to execute each transmission, UEs may be allowed to transmit autonomously in specific resource regions of frequency, time and/or code. Blind detection of transmissions may require the UEs to use some type of identifier so that the BS can identify the source of each transmission.
An issue with including a MAC ID (or similar identifier) in each transmission is that the signaling resource overhead can be quite large compared to the data transmitted, especially in cases where the amount of data transmitted is small. For example, a source identification (ID) may be 16 bits, 32 bits, 48 bits, 128 bits or even longer in length, whereas the data coming from a transmitter may be 20-30 bits (e.g. temperature reading). Even in blind or grant-free transmission networks (i.e., networks that do not use control messages to schedule/grant transmissions), a certain amount of overhead is still used to explicitly signal and identify the source of transmissions.